Chris,
I voted for the Challenger, although, there isn't a bad choice on that list. All would be excellent and fun vehicles. Few things you need to think about tho. I love Vipers. But, as a primary driver, it makes no sense. They are very tight, huge plastic console (on the Gen I and IIs, which are my faves as well), not roomy, not a good ride, not insurance friendly, and if you ruin a clamshell hood, welp, you're on your own. (~$15k) Also, mods are an arm, leg, and a nut.
The LS-based cars (you know my background, 00 WS-6, 99 Hugger SS, 03 EB/MR Z-06) are affordable, and fairly easy to mod and tune. Not much to em, tho.
The QC is a great truck (just sold mine), but just be ready for the fuel bill. Having said that, it's hard not to pick the QC from this list.
The SRT-8 (although not my favorite 'skin' on it
) is an AWESOME CAR. AWESOME. Would be a great choice.
The Challenger should be pretty sweet. If it werent for the power plant coming in the Shelby, I'd prolly also be on the list for one. But I want to mod the absolute piss out of something, and it's got the platform I want to start with (forged internals, 8.5:1 CR, 500hp at only 9psi, dynoing 489 to the wheels!) If you want something that starts with 500hp, and is as easy to mod as your current ride, check it out. $500 bucks in mods should put you around ~600hp. They are also (FoMoCo) carrying a twin screw option,
that should be good into the mid 700's (I know you have been, Ive seen you on svteperformance.com) Ive got a few other sites with better info than that <----1, if you'd like, hit me up.
As for me, I think my next choice is made up.
Now to pick the color, and find a dealer not crooked as a ? mark to place an order. Plan on going with all options, except for shaker 1000 system upgrade.
Color combo is going to be difficult part.
Right now, leaning towards Grabber Orange with either White or the Tungsten stripes. Let us know what you decide, and good luck on your very difficult choice!